react 三个点代表什么

var people=['Wayou','John','Sherlock'];
//sayHello函数本来接收三个单独的参数人一，人二和人三
function sayHello(people1,people2,people3){
    console.log(`Hello ${people1},${people2},${people3}`);
}
//但是我们将一个数组以拓展参数的形式传递，它能很好地映射到每个单独的参数
sayHello(...people);//输出：Hello Wayou,John,Sherlock 
//而在以前，如果需要传递数组当参数，我们需要使用函数的apply方法
sayHello.apply(null,people);//输出：Hello Wayou,John,Sherlock

var props = {};
  props.foo = x;
  props.bar = y;
  var component = ;
  
//等价于
var props = {};
  props.foo = x;
  props.bar = y;
  var component = ;

var props = { foo: 'default' };
var component = ;
console.log(component.props.foo); // 'override'